Sept. 15 update: Police have now named Gabby Petito’s fiancé a ‘person of interest’ in her disappearance.

TAMPA, Fla. (WFLA/WPIX/NBC) — Authorities in New York are investigating the disappearance of a North Port, Florida woman who went missing on a cross-country trip with her fiancé.

The Suffolk County Police Department on Sunday appealed to the public for help in finding 22-year-old Gabby Petito, saying she was last known to be in Wyoming’s Grand Teton National Park, and had been traveling with her fiancé in a white 2012 Ford Transit van with a Florida license plate, which police said has since been recovered.

Petito is described as about 5 feet 5 inches tall and 110 pounds with blonde hair and blue eyes, and several tattoos. A tattoo on her forearm says “let it be.”

Gabrielle Petito sent updates to her family several times a week after the trip started on July 2. Her mom Nichole Schmidt last heard from Petito on Aug. 30. At first, she assumed her daughter was somewhere without service.

“I believed she was in a place with no service,” Schmidt said. “It was day eight, nine that I really became concerned and I figured she couldn’t be off the grid for that long.”

Now she’s asking anyone who might have seen her daughter to come forward.

“She could be alone somewhere,” Schmidt said. “She could be stranded somewhere in the wilderness and she needs help.”

News outlets report Petito had moved with her fiancé from Blue Point, New York, to North Port, Florida, two years ago. They set off on a cross-country trip in July and documented their travels every step of the way in photos and videos posted to YouTube and Instagram under the name “Nomadic Statik.”

“If you look at her Instagram page, you can actually find a lot of evidence of where they were these past few months,” said Schmidt.

Schmidt says the couple’s posts slowed down toward the end of August, and so did their communication. Then Petito stopped responding altogether.

“The last text I got from her was on Aug. 30. I don’t know if that was her texting me or not,” Schmidt said.

Petito has five siblings, Schmidt said. While the younger ones don’t quite understand what’s going on, it’s been difficult for her older siblings.

“It’s scary and it’s nerve-wracking. We don’t eat, we don’t sleep,” Schmidt said. “We’re just actively looking for her.”

Schmidt said the family reached out to law enforcement agencies in Florida and New York. Police in Suffolk County agreed to file a missing person’s report on Sunday. They are asking anyone with information about Petito’s whereabouts to call Crime Stoppers at 1-800-220-TIPS.

According to the family, her fiancé returned home to Florida, has hired an attorney and is refusing to cooperate with the investigation into their daughter’s disappearance, Newsday reported. He has not been named as a suspect or been associated with her disappearance by police.

North Port police released a statement saying they do not know if the crime happened in the municipality, but are looking into the matter with Suffolk County police:

The North Port Police Department is actively assisting in this case in conjunction with the Suffolk County Police Department where she was reported missing. We currently have no definitive information that a crime took place here in North Port. With that said, the circumstances are odd. The vehicle she was traveling in was located here in North Port. So, we are actively gathering local details and any evidence to assist in finding needed answers. If you know anything about this case please contact us at 941-429-7382.

North Port Police Department

The FBI Tampa Field Office is also looking into the situation. Tips can be sent by calling 1-800 CALL FBI or online through